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1.
The synthesis of a number of 1,1'-disubstituted ferrocene-containing compounds is described; the structures of the compounds containing the ferrocene unit are related to those of mesogenic systems containing a 1,4-disubstituted benzene ring or a trans-1,4-cyclohexyl ring. Direct comparisons are made between the aryl-, cyclohexyl- and ferrocene-containing compounds in order to assess the effect on transition temperatures of replacing a benzene or cyclohexyl ring with a ferrocene unit. In comparison with conventional ring systems the ferrocene unit causes substantial reductions in clearing temperatures. 相似文献
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Ana T.P.C. GomesAnna C. Cunha Maria do Rosário M. DominguesMaria G.P.M.S. Neves Augusto C. ToméArtur M.S. Silva Fernanda da C. SantosMaria C.B.V. Souza Vitor F. FerreiraJosé A.S. Cavaleiro 《Tetrahedron》2011,67(38):7336-7342
New porphyrin/4-quinolone conjugates were synthesized from the Suzuki-Miyaura coupling reaction of a β-borylated porphyrin with bromo-4-quinolones containing N-ethyl and N-d-ribofuranosyl substituents. The use of electrospray ionization tandem mass spectrometry showed important information about the fragmentation pathways of the new compounds. It was possible to distinguish between those compounds with the porphyrin moiety linked at the 6-position of the quinolone unit from their 7-substituted isomers. The new compounds showed to be good singlet oxygen generators. 相似文献
4.
《Liquid crystals》1997,22(5):557-561
A new series of ferroelectric liquid crystal materials containing a lateral methyl group on the aromatic ring of the alkoxybenzoate unit has been synthesized and investigated. These materials exhibit a wide temperature range of ferroelectric SmC* phase on cooling (including supercooling) with a very high spontaneous polarization. All phase transition temperatures are lower when compared with those of similar non-substituted materials. In comparison with the compounds containing the lateral methoxy group, only the SmC*-Cr transition changed significantly. The values of spontaneous polarization are mostly increased compared with both non-substituted and methoxy substituted compounds. 相似文献
5.
J.S. Bradshaw S.L. Baxter D.C. Scott J.D. Lamb R.M. Izatt J.J. Christensen 《Tetrahedron letters》1979,20(36):3383-3386
A new series of macrocyclic polyether-diester ligands containing a furan subcyclic unit is reported. In contrast to other macrocyclic ligands, the twenty-four membered ring diester compounds containing either a furan or benzene subcyclic unit complex more strongly with benzylammonium perchlorate than do the eighteen membered ring compounds. 相似文献
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Jia-Hong Wu Dr. Jian-Ping Tan Jia-Yan Zheng Jiajia He Prof. Dr. Zhenlei Song Prof. Dr. Zhishan Su Prof. Dr. Tianli Wang 《Angewandte Chemie (International ed. in English)》2023,62(13):e202215720
Given the comparatively lower rotational barriers, the catalytic asymmetric construction of axially chiral biaryl structures, especially those containing a five-membered heterocycle, still remains a challenge. Herein, we described a general and modular protocol to access atropisomeric arylpyrazole scaffolds containing a phosphorus unit by a dipeptide phosphonium salt catalyzed reaction involving an oxidative central-to-axial chirality conversion. This reaction features excellent yields and enantioselectivities, broad substrate scope, and a low catalyst loading, delivering axially chiral phosphine compounds. 相似文献
8.
Anderson KM Goeta AE Hancock KS Steed JW 《Chemical communications (Cambridge, England)》2006,(20):2138-2140
A series of Cambridge Structural Database studies show that ionic species generally form low Z' structures, even in those cases where charge assisted hydrogen bonding is a key feature, e.g. oxo-anion complexes. By introducing a competing pi-pi stacking interaction, two oxo-anion compounds are shown to crystallise with more than one molecule in the asymmetric unit, including the first hydrogen phosphate containing structure to have Z' > 2. 相似文献
9.
Jerald S. Bradshaw Peter Huszthy Hiroyuki Koyama Steven G. Wood Scott A. Strobel Richard B. Davidson Reed M. Izatt N. Kent Dalley John D. Lamb James J. Christensen 《Journal of heterocyclic chemistry》1986,23(6):1837-1843
Three new proton-ionizable macrocyclic polyether ligands containing the 4-pyridone subcyclic group have been prepared. Two of these ligands contain lipophilic n-octyl substituents, the other ligand contains a phenyl substituent. The 15-crown-5 ligand containing both a 4-pyridone subcyclic unit and an n-octyl substituent selectively transported lithium cations in a water-methylene chloride-water bulk liquid membrane system. Five crown compounds containing the 4-pyridone subcyclic unit were converted to the 4-thiopyridono-crown compounds when treated with Lawesson's Reagent. The crystal structure of 4-thiopyridono-18-crown-6 shows a carbon-sulfur double bond and a molecule of water hydrogen bonded inside the macrocycle cavity. 相似文献
10.
Akhtaruzzaman M Tomura M Nishida J Yamashita Y 《The Journal of organic chemistry》2004,69(9):2953-2958
Novel dipyridyl compounds containing a mono- and bisbenzothiadiazole unit were synthesized using the Stille coupling reaction. Their pyridinium salts, viologen analogues, were also prepared by the N-alkylation. The X-ray crystallographic analysis of the compounds containing a benzothiadiazole ring revealed nonplanar molecular structures and unique crystal structures depending on the nitrogen positions. The dipyridyl compounds are efficient fluorophores with high electron affinity. The derivative afforded complexes with chloranilic acid and cyanuric acid composed of hydrogen bonding networks. The methyl viologen analogues showed two-stage one-electron reduction waves. 相似文献
11.
Domenico Acierno Simona Concilio Angela Diodati Pio Iannelli Stefano P. Piotto Paola Scarfato 《Liquid crystals》2002,29(11):1383-1392
The synthesis and characterization of low molecular mass compounds containing 1,4-bis(5-phenyl-1,3,4-oxadiazolyl)benzene is reported. All compounds are fluorescent in solution. Due to the flat shape of the conjugated unit, smectic-like packing is observed at high temperatures for some of the synthesized compounds. Moreover the insertion of a lateral flexible alkoxy unit strongly destabilizes the smectic order whilst promoting the appearance of a nematic phase in the case of the shortest methoxy unit. The mesogenic character of this unit may be of interest in the synthesis of liquid crystalline polymeric systems, taking advantage of both the fluorescent properties and the peculiar molecular structure of the liquid crystalline state. 相似文献
12.
Domenico Acierno Simona Concilio Angela Diodati Pio Iannelli Stefano P. Piotto Paola Scarfato 《Liquid crystals》2013,40(11):1383-1392
The synthesis and characterization of low molecular mass compounds containing 1,4-bis(5-phenyl-1,3,4-oxadiazolyl)benzene is reported. All compounds are fluorescent in solution. Due to the flat shape of the conjugated unit, smectic-like packing is observed at high temperatures for some of the synthesized compounds. Moreover the insertion of a lateral flexible alkoxy unit strongly destabilizes the smectic order whilst promoting the appearance of a nematic phase in the case of the shortest methoxy unit. The mesogenic character of this unit may be of interest in the synthesis of liquid crystalline polymeric systems, taking advantage of both the fluorescent properties and the peculiar molecular structure of the liquid crystalline state. 相似文献
13.
Fernando Navarro Jos Luis Serrano 《Journal of polymer science. Part A, Polymer chemistry》1989,27(11):3691-3701
Two homologous series of flexible main chain liquid crystalline polyesters with isomeric mesogenic groups containing conjugated double bonds, were synthesized and studied by differential scanning calorimetry and optical microscopy. One series (S1) has the p-phenylene-diacryloyloxydibenzoyl moiety as a mesogenic unit. The other (S2) has the terephtaloyl dioxydicinnamoyl moiety as a mesogenic unit. The reactivity of the conjugated double bonds of the p-phenylenediacryloxy unit, at the temperature of mesophase formation, impedes the stability of liquid crystalline mesophases of polymers of series (S1). Two low molecular weight analogues of polymers were also prepared and their properties compared with those of polymers of similar structure. The two model compounds form stable smectic mesophases over a wide range of temperatures, which shows the high mesomorphogenic ability of both mesogenic units. 相似文献
14.
The formal kinetic peculiarities of the decomposition of polyfunctional compounds containing several identical reaction groups were used to determine the stepwise character of secondary reactions and to interpret their chemical mechanism. It was found that the degradation of difluoramines, azides, nitro esters, and aliphatic and aromatic nitro compounds always occurred stepwise via long-lived intermediate products. Only nitramines with closely spaced reaction centers exhibited deviations from this mechanism. 相似文献
15.
The well known reaction between 2,2-dimethoxypropane and water allows for the conversion of an aqueous into an organic solution ready to be injected directly into a gas chromatographic-mass spectrometric (GC-MS) system. Only time, temperature and water/ketal ratio were the parameters studied among those which influence the equilibrium reaction. The reaction environment is not suitable for all compounds: acids, esters, alcohols, amines, ketones and phenols may react with methanol, acetone and ketal owing to Amberlyst being present as catalyst. This method is proposed for the GC-MS analysis of aqueous solutions containing hydrocarbons, halogenated hydrocarbons and ethers. The determination of some pesticides in water is reported. 相似文献
16.
Summary Room temperature ionic liquids (RTIL) are molten salts with melting points well below room temperature. 1-butyl-3-methylimidazolium
chloride is a typical example of such RTIL. It was used as a solvent to dissolve permethylated-β-cyclodextrin (BPM) and dimethylated-?cyclodextrin
(BDM) to prepare stationary phases for capillary columns in gas chromatography for chiral separation. The RTIL containing
columns were compared to commercial columns containing the same chiral selectors. A set of 64 chiral compounds separated by
the commercial BPM column was tested on the RTIL BPM column. Only 21 were enantioresolved. Similarly, a set of 80 compounds
separated by the commercial BDM column was passed on the RTIL BDM column with only 16 positive separations. It is proposed
that the imidazolium ion pair could make an inclusion complex with the cyclodextrin cavity, blocking it for chiral recognition.
All the chiral compounds recognized by the RTIL columns had their asymmetric carbon that was part of a ring structure. The
retention factors of the derivatized solutes were lower on the RTIL columns than those obtained on the commercial equivalent
column. The peak efficiencies obtained with the RTIL capillary were significantly higher than that obtained with the commercial
column. These observations may contribute to the knowledge of the mechanism of cyclodextrin-based GC enantioselective separations. 相似文献
17.
Jung-Il Jin E-Joon Choi Seog-Chul Ryu 《Journal of polymer science. Part A, Polymer chemistry》1987,25(1):241-249
Two new series of thermotropic polyesters were prepared and their mesomorphic properties were investigated. The polymers consist of triad aromatic ester-type mesogenic units with decamethylene spacers. The mesogenic units of the first series are composed of isomeric dihydroxynaphthalene moieties as the central structure flanked by two p-oxybenzoyl groups. In the second series the mesogenic units were of reversed ester linkages: the central moieties, derived from 1,4-naphthalene dicarboxylic acid, trans-1,4-cyclohexanedicarboxylic acid, or 2,5-pyridinedicarboxylic acid, are connected on both sides to p-phenylene structures. Two low molecular weight model compounds with 1,4-naphthylene unit at the center of the mesogenic unit were synthesized and their mesomorphic properties were compared with those of corresponding polymers. It was observed both for the model compounds and the polymers containing 1,4-naphthylene units that the linking order of the ester group in the mesogenic unit exerted a decisive influence on the capability for the formation of a mesophase. Thermal and mesomorphic properties were investigated by DSC, on a polarizing microscope equipped with a hot-stage, and by visual observation of stir-opalescence of the melts. 相似文献
18.
《液相色谱法及相关技术杂志》2012,35(3):431-444
Abstract The deletion of a methylene unit from the arylamine side chain of the 3,4-methylenedioxyamphetamines (MDAs) produces the homologous 1-(3,4-methylenedioxyphenyl)-1-ethanamines. These ethanamines were prepared via reductive amination of the corresponding ketone with a series of N-alkylamines. Analytical methods were developed to distinguish these compounds from the MDA series. The ethanamines were separated under reversed-phase1 iquid chromatographic conditions using a c18 stationary phase and a mobile phase of aqueous acidic (pH3) acetonitrite containing triethylamine. The electron impact mass spectra of the ethanamines were determined by GC-MS and the fragmentation pattern clearly distinguishes these compounds from those of the MDA series having the same molecular weight. 相似文献
19.
The synthesis of new organophosphorus compounds containing a carbamoyl unit is performed by nucleophilic addition or cycloaddilion on substituted acetylisocyanates. 相似文献
20.
Remko Achten Ruud Cuypers Marcel Giesbers Arie Koudijs Antonius T. M. Marcelis Ernst J. R. Sudh lter 《Liquid crystals》2004,31(8):1167-1174
Two series of asymmetric banana-shaped compounds have been synthesized and studied. In the 1,3-phenylene bis[4-(4'-alkoxybenzoyloxy)]benzoate series the lack of symmetry was derived solely from the difference in length of the two terminal alkoxy chains. In the 3,4'-biphenylene bis[4-(4'-alkoxybenzoyloxy)]benzoate series the asymmetric nature originates from the 3,4'-substitution of the central biphenyl group and from the difference in length of the two terminal chains. All the melting points of the asymmetrical compounds in the series with the central phenyl unit are lower than those of the symmetrical compounds. The liquid crystalline B1 or B2 phase was retained in all cases. In the series with the central biphenyl unit the compounds with the shortest chain attached to the para-position of the central biphenyl unit have the lowest melting points. A significant lowering of the melting points in comparison with the symmetrically substituted compounds, however, could not be achieved. All the compounds of both series show a layer spacing which is comparable to those of the symmetrically substituted parent compounds. The observed switching behaviour of both the symmetric and asymmetric compounds with a B2 phase was antiferroelectric. 相似文献